:root {
  /* 562.5 / 750 562.5是屏幕逻辑尺寸 750是设计尺寸 $size是750基准设计尺寸 */
  --proportion: 0.75;
}

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  font-weight: normal;
}

ul {
  list-style: none;
}


